Thursday, 14 June 2012

Mosquitoes Genetically Modified To Be Incapable Of Transmitting Malaria

Plasmodium falciparum enters erythrocytes and digests the haemoglobin before multiplying until the cell ruptures.

False colour Scanning Electron Micrograph

Scientists at the University of Californaia Irvine and the Pasteur Institute in Paris have successfully created a model of the Anopheles stephensi mosquito - a major source of malaria in India and the Middle East - that impairs the development of the malaria parasite. These mosquitoes, in turn, cannot transmit the disease through their bites.

"Our group has made significant advances with the creation of transgenic mosquitoes," said Anthony James, a UCI Distinguished Professor of microbiology & molecular genetics and molecular biology & biochemistry. "But this is the first model of a malaria vector with a genetic modification that can potentially exist in wild populations and be transferred through generations without affecting their fitness."

According to the World malaria report 2011, there were about 216 million cases of malaria and an estimated 655 000 deaths in 2010. It is currently the 15th most common cause of death in the world, with 91% of cases located in Africa.

James said one advantage of his group's method is that it can be applied to the dozens of different mosquito types that harbor and transmit the Plasmodium falciparum parasite, including those in Africa.

Anthony James and his team infected mice with the human form of malaria which caused the mouse to produce antibodies to the combat the parasite; They then exploited the molecular components of this mouse immune-system response and engineered genes that could produce the same response in mosquitoes. In their model, antibodies are released in genetically modified mosquitoes that render the parasite harmless to others.

"We see a complete deletion of the infectious version of the malaria parasite," said James, a member of the National Academy of Sciences. "This blocking process within the insect that carries malaria can help significantly reduce human sickness and death."

Comments:

Although the engineered genes could have been found in wild species of mosquito due to random genetic mutations, the time scale on which the prevalance of the gene would be widespread is debatable. Another concern is that the modification is passed on from generation to generation of mosquito, which could be seen as "playing God" with nature. Many wish to leave genetics alone as we have no right to interfere with nature.